If you want it lightly refreshed (like out of the refrigerator), no ice is needed. But if you want a frosty drink, add a handful of ice to the blender (unless you are using frozen blueberries, then ice isn’t needed).
Want to make 2 of these, one for now, one for tomorrow? Simply cover with a lid and place in the refrigerator for up to 1 day. Shake the jar before serving.